In both mobile and land-line telephone systems, speaker-phone systems have been utilized to allow a user to communicate with another party without using a handset. Conventional speaker-phone systems usually include a microphone to transmit communications from the user and a speaker to transmit the incoming signals received from the other party communicating with the user.
In certain environments, the presence of background noise may distract and/or make it quite difficult for the user to hear the other party. For example, when using a speaker-phone system in a vehicle, the user is exposed to a variety of undesirable background noises introduced by the engine, exhaust system and tires as well as other noises. The presence of these background noises can interfere and reduce the ability of the user to hear the other party.
Accordingly, there is a need to eliminate or reduce undesirable signals within a particular environment. There is also a need to cancel undesired signals having a variety of frequency ranges and signals having a regular periodic or recurring component.
A preferred embodiment of the invention, is now described, by way of example only, with reference to the drawings.